diff options
author | Dave Martin <dave.martin@linaro.org> | 2012-08-10 12:53:24 +0100 |
---|---|---|
committer | Sascha Hauer <s.hauer@pengutronix.de> | 2012-08-13 21:33:14 +0200 |
commit | 7095b95654302ceb8a011ee883d1500851061b0d (patch) | |
tree | d93d153741e33763191e1c3837cb981708e07456 /arch/arm/plat-mxc | |
parent | a745f039b901b43937f61f149ad9cee2796ed299 (diff) |
ARM: mxc: ssi-fiq: Make ssi-fiq.S Thumb-2 compatible
Because FIQ handlers get copied straight into the vectors page to
the FIQ vector entry point, FIQ handlers in a Thumb-2 kernel must
start in Thumb-2. A Thumb-2 kernel enters all exception vectors in
Thumb-2.
This patch adapts the mxc SSI FIQ code suitable for a Thumb-2
kernel.
The code contained use of r13 (sp) which isn't allowed in Thumb-2.
r11 and r13 have been swapped throughout the file to work around
this.
Currently, the way that the function to be copied is located using
labels is a bit ugly: we cannot annotate the FIQ handler properly
as a Thumb-2 function, because this would set bit 0 of the label
address seen by the linker, causing off-by-one errors when copying
the function. Ideally, the copy would be done with fncpy(), but
this would require changes to the common set_fiq_handler()
function. For now, we don't touch this.
References to locally-defined global symbols with adr and ldr may
not be accepted by the assembler in Thumb-2. Local shadow symbols
are added to work around this.
Signed-off-by: Dave Martin <dave.martin@linaro.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Diffstat (limited to 'arch/arm/plat-mxc')
-rw-r--r-- | arch/arm/plat-mxc/ssi-fiq.S | 89 |
1 files changed, 50 insertions, 39 deletions
diff --git a/arch/arm/plat-mxc/ssi-fiq.S b/arch/arm/plat-mxc/ssi-fiq.S index 8397a2dd19f..a8b93c5f29b 100644 --- a/arch/arm/plat-mxc/ssi-fiq.S +++ b/arch/arm/plat-mxc/ssi-fiq.S @@ -34,91 +34,98 @@ .global imx_ssi_fiq_rx_buffer .global imx_ssi_fiq_tx_buffer +/* + * imx_ssi_fiq_start is _intentionally_ not marked as a function symbol + * using ENDPROC(). imx_ssi_fiq_start and imx_ssi_fiq_end are used to + * mark the function body so that it can be copied to the FIQ vector in + * the vectors page. imx_ssi_fiq_start should only be called as the result + * of an FIQ: calling it directly will not work. + */ imx_ssi_fiq_start: - ldr r12, imx_ssi_fiq_base + ldr r12, .L_imx_ssi_fiq_base /* TX */ - ldr r11, imx_ssi_fiq_tx_buffer + ldr r13, .L_imx_ssi_fiq_tx_buffer /* shall we send? */ - ldr r13, [r12, #SSI_SIER] - tst r13, #SSI_SIER_TFE0_EN + ldr r11, [r12, #SSI_SIER] + tst r11, #SSI_SIER_TFE0_EN beq 1f /* TX FIFO empty? */ - ldr r13, [r12, #SSI_SISR] - tst r13, #SSI_SISR_TFE0 + ldr r11, [r12, #SSI_SISR] + tst r11, #SSI_SISR_TFE0 beq 1f mov r10, #0x10000 sub r10, #1 and r10, r10, r8 /* r10: current buffer offset */ - add r11, r11, r10 + add r13, r13, r10 - ldrh r13, [r11] - strh r13, [r12, #SSI_STX0] + ldrh r11, [r13] + strh r11, [r12, #SSI_STX0] - ldrh r13, [r11, #2] - strh r13, [r12, #SSI_STX0] + ldrh r11, [r13, #2] + strh r11, [r12, #SSI_STX0] - ldrh r13, [r11, #4] - strh r13, [r12, #SSI_STX0] + ldrh r11, [r13, #4] + strh r11, [r12, #SSI_STX0] - ldrh r13, [r11, #6] - strh r13, [r12, #SSI_STX0] + ldrh r11, [r13, #6] + strh r11, [r12, #SSI_STX0] add r10, #8 - lsr r13, r8, #16 /* r13: buffer size */ - cmp r10, r13 - lslgt r8, r13, #16 + lsr r11, r8, #16 /* r11: buffer size */ + cmp r10, r11 + lslgt r8, r11, #16 addle r8, #8 1: /* RX */ /* shall we receive? */ - ldr r13, [r12, #SSI_SIER] - tst r13, #SSI_SIER_RFF0_EN + ldr r11, [r12, #SSI_SIER] + tst r11, #SSI_SIER_RFF0_EN beq 1f /* RX FIFO full? */ - ldr r13, [r12, #SSI_SISR] - tst r13, #SSI_SISR_RFF0 + ldr r11, [r12, #SSI_SISR] + tst r11, #SSI_SISR_RFF0 beq 1f - ldr r11, imx_ssi_fiq_rx_buffer + ldr r13, .L_imx_ssi_fiq_rx_buffer mov r10, #0x10000 sub r10, #1 and r10, r10, r9 /* r10: current buffer offset */ - add r11, r11, r10 + add r13, r13, r10 - ldr r13, [r12, #SSI_SACNT] - tst r13, #SSI_SACNT_AC97EN + ldr r11, [r12, #SSI_SACNT] + tst r11, #SSI_SACNT_AC97EN - ldr r13, [r12, #SSI_SRX0] - strh r13, [r11] + ldr r11, [r12, #SSI_SRX0] + strh r11, [r13] - ldr r13, [r12, #SSI_SRX0] - strh r13, [r11, #2] + ldr r11, [r12, #SSI_SRX0] + strh r11, [r13, #2] /* dummy read to skip slot 12 */ - ldrne r13, [r12, #SSI_SRX0] + ldrne r11, [r12, #SSI_SRX0] - ldr r13, [r12, #SSI_SRX0] - strh r13, [r11, #4] + ldr r11, [r12, #SSI_SRX0] + strh r11, [r13, #4] - ldr r13, [r12, #SSI_SRX0] - strh r13, [r11, #6] + ldr r11, [r12, #SSI_SRX0] + strh r11, [r13, #6] /* dummy read to skip slot 12 */ - ldrne r13, [r12, #SSI_SRX0] + ldrne r11, [r12, #SSI_SRX0] add r10, #8 - lsr r13, r9, #16 /* r13: buffer size */ - cmp r10, r13 - lslgt r9, r13, #16 + lsr r11, r9, #16 /* r11: buffer size */ + cmp r10, r11 + lslgt r9, r11, #16 addle r9, #8 1: @@ -126,11 +133,15 @@ imx_ssi_fiq_start: subs pc, lr, #4 .align +.L_imx_ssi_fiq_base: imx_ssi_fiq_base: .word 0x0 +.L_imx_ssi_fiq_rx_buffer: imx_ssi_fiq_rx_buffer: .word 0x0 +.L_imx_ssi_fiq_tx_buffer: imx_ssi_fiq_tx_buffer: .word 0x0 +.L_imx_ssi_fiq_end: imx_ssi_fiq_end: |